In general, the dryer dries objects, such as clothes, and the like, with air heated by electric heater, or a gas burner.
FIG. 1 illustrates a perspective disassembled view of key parts of a related art dryer. Referring to the drawing, there is a drum 1 fitted inside of a cabinet (not shown) that forms an outside shape of the dryer. The drum 1 is cylindrical, with opposite opened ends, and has a belt groove 2 along an outside circumference of a middle of the drum 1 for winding a drum belt 4 driven by a motor 3. The drum 1 has a drying chamber 5 therein for carrying out drying. The drum 1 has a plurality of lifters 6 therein for lifting and dropping drying objects in the drying chamber 5, to turn the drying objects upside down for improving a drying efficiency when the drum 1 is rotated.
The drum 1 is provided with a front supporter 7 and a rear supporter 9 fitted to a front end and a rear end thereof, oppositely. The front supporter 7 and the rear supporter 9 close opened parts of the drum 1, to form the drying chamber 5, and support the front end and the rear end of the drum 1. There are sealing members 10 fitted between the front supporter 7 and the drum 1 to be rotated, and the rear supporter 9 and the drum 1 to be rotated for prevention of leakage. Of course, there are a plurality of rollers (not shown) provided at required positions of the front supporter 7 and the rear supporter 9 of the drum 1, for supporting the drum 1.
The front supporter 7 has an opening 8 for making inside and outside of the drying chamber 5 in communication. The opening 8 is selectively opened by a door (not shown).
The rear supporter 9 is fitted with a heated air supply duct 12, in communication with the drying chamber 5, for serving as a passage for supplying heated air to the drying chamber 5.
There is an outlet assembly 13 at one side of the front supporter 7 at a bottom of the opening 8 of the front supporter 7, for escaping of air. The outlet assembly 13 is provided with a lint filter 14.
The lint filter 14 filters foreign matters (for example, lint and dust) contained in the air escaping from the drying chamber 5.
There is a lint duct 15 in communication with the outlet assembly 13, wherein the lint filter 14 is positioned even inside of the lint duct 15. There is a blower 17 connected to the lint duct 15, for drawing air from inside of the drying chamber 5 through the lint duct 15. The blower 17 is fitted to an inside of a blower housing 18 having one side in communication with the lint duct 15 and the other side connected to an air discharge pipe 19. Therefore, the air, escaped from the drying chamber 5 and passed through the lint duct 15, is discharged to an outside through the air discharge pipe 19 by the blower 17.
In the meantime, there is a guide funnel 20 connected to an inlet of the heated air supply duct 12. The guide funnel 20 guides the heated air produced by burning the gas to the inlet of the heated air supply duct. There is a mixing tube 24 at the inlet of the guide funnel 20 for mixing the gas injected from the gas nozzle 22 with primary air. The mixing tube 24 has an outlet positioned a distance inside of the guide funnel 20.
The gas nozzle 22 is fitted opposite to the inlet of the mixing tube 24, and has a valve 30 connected thereto for controlling gas supply and an amount of the gas supply. The valve 30 has a gas tube 23 connected thereto for continuous supply of gas from a gas supply source.
Accordingly, the gas injected from the gas nozzle 22 and external air introduced through the inlet of the mixing tube 24, i.e., the primary air, are mixed inside of the mixing tube 24.
The operation of the foregoing related art dryer will be explained.
Upon pressing a starting button after laundry, drying objects, is introduced into the drying chamber 5 in the drum 1, and a door thereon is closed, the drum 1 starts to rotate as the drum belt 4 wound around the belt groove 2 is driven by the motor 3. As the blower 17 starts, the air inside of the drying chamber 5 is drawn through the lint duct 15. Then, external air is introduced into the drying chamber 5 through the air supply duct 12 owing to a pressure difference.
The air to the heated air supply duct 12 is heated to a relatively high temperature by the gas burner. The gas is injected to an inside of the mixing tube 24 through the gas nozzle 22, the primary air is introduced to the inlet of the mixing tube 24, the gas and the primary air are mixed in the mixing tube 24, and ignited at the outlet of the mixing tube 24 by a spark plug 26 initially, thereby burned. A thermal energy generated as the gas is burned is introduced into the guide funnel 20, and heats the introduced air, to produce the heated air.
Meanwhile, the heated air is introduced into the drying chamber 5 in the drum 1 through the heat air supply duct 12. The heated air absorbs moist in laundry in the drying chamber 5, and escapes the drying chamber 5 through the outlet assembly 13. The air is made to escape the drying chamber 5 through the outlet assembly by a suction force of the blower 17. The foreign matters, such as dust, and lint in the air escaping through the outlet assembly 13 are filtered at the lint filter 14.
However, the foregoing related art has the following problems.
The single circular sectioned outlet of the mixing tube 24 causes to form one large and long flame as shown in FIG. 3 at the outlet of the mixing tube 24. The flame differs in size, length, and position of formation of the flame depending on a number of revolution of the blower, air resistance, and the like.
For an example, when the blower 17 has an appropriate number of revolution, though the flame ‘F’ is formed close to the outlet of the mixing tube 24, when the blower 17 has an excessively high number of revolution, a lifting phenomenon is occurred in which the flame ‘F’ is formed at a point a distance ‘1’ away from the outlet of the mixing tube 24.
When the blower 17 runs at an excessively low number of revolutions, the flame ‘F’ becomes very long, such that the flame reaches to the heated air supply duct, and heats the heated air supply duct excessively, and, to the drying chamber 5 and starts fire when the flame becomes excessively long.
In other words, in the related art, if external conditions, such as the number of revolutions of the blower, and the like are not appropriate, a balance between a combustion rate of the gas and an amount of introduced air is broken, to cause lifting, or the flame to reach to an inside of the drum as the flame becomes excessively long.
Moreover, when the flame becomes longer, entire heat can not be used for heating the air, but much of the heat is taken away by adjacent components as the flame reaches close to the adjacent components, that increases heat loss.
In the related art, the initial ignition capability is poor because the gas mixed with the primary air exits the outlet of the mixing tube 24 right away.
The single circular sectioned outlet of the mixing tube 24 causes the flame ‘F’ to have a form of a lump, which reduces a contact area of the flame ‘F’ with the secondary air. That is, if the flame ‘F’ has the form of a lump, the contact area of the flame ‘F’ with the secondary air is reduced on the whole, to cause incomplete combustion as there is lack of air at an inner part of the flame, that also acts as a cause of a long flame.
Moreover, the insufficient secondary air supply to the flame ‘F’ causes the flame, not only to become longer, but also to turn yellowish, with incomplete combustion, to produce much soot and hazardous gases (CO, NOx, SOx).